To satisfy demands for wireless data traffic having increased since commercialization of 4th-Generation (4G) communication systems, efforts have been made to develop improved 5th-Generation (5G) communication systems or pre-5G communication systems. The 5G communication system or the pre-5G communication system is called a beyond-4G-network communication system or a post-long term evolution (LTE) system.
To achieve a high data rate, implementation of the 5G communication system in an ultra-high frequency (mmWave) band (e.g., a 60 GHz band) is under consideration. In the 5G communication system, beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), an array antenna, analog beamforming, and large-scale antenna technologies have been discussed to alleviate a propagation path loss and to increase a propagation distance in the ultra-high frequency band.
For system network improvement, in the 5G communication system, techniques such as an evolved small cell, an advanced small cell, a cloud radio access network (RAN), an ultra-dense network, a device to device (D2D) communication, a wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMPs), and interference cancellation have been developed.
In the 5G system, advanced coding modulation (ACM) schemes including hybrid frequency-shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC), and advanced access schemes including filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed.
A wireless communication system is now evolving to support a high data rate and to install many access points (APs), so as to satisfy demands for wireless data traffic and wireless connectivity of continuously increasing terminals. For example, to increase a data rate, a communication system is being developed to improve spectral efficiency and to increase a channel capacity based on various schemes such as orthogonal frequency division multiplexing (OFDM) and MIMO.
In a wireless local area network (WLAN) system, multiple user-MIMO (MU-MIMO) has been used to support a large-volume data service in which multiple users and multiple antennas are used together.
The Institute of Electrical and Electronics Engineers (IEEE) has conducted standardization under consideration of an overlapping basic service sets (OBSS) environment in which overlapping WLANs co-exist to support drastically increasing traffic volume and wireless terminals in WLAN systems.
A medium access control (MAC) protocol based on IEEE 802.11 operating in a contention-based manner regards two or more signal transmissions as a collision if two or more signals are simultaneously transmitted at a particular point in time. Thus, different terminals and APs using the same channel occupy the channel through mutual contentions to use the channel.
In the OBSS environment where overlapping multiple terminals and multiple APs co-exist, the number of terminals and APs using the same channel in the OBSS environment is large, resulting in a high probability of occurrence of a collision. Moreover, terminals beyond their sensing coverages may fail in observing each other and thus attempt transmission, degrading received signal performance, which is referred to as a hidden node problem, and excessively many terminals exist in the sensing coverage and hardly attempt transmission, which is referred to as an exposed node problem. These problems are very serious in the OBSS environment, eventually causing the entire network performance degradation.
Thus, in the OBSS environment where overlapping WLAN networks using the same channel exist, standardization for studying a scheme for alleviating interference between BSSs and improving performance by changing parameters of each BSS, for example, sensing power, channel, transmission power, and beamforming direction, is underway based on IEEE 802.11.
However, for interference control and performance improvement in the OBSS environment where multiple BSSs coexist, a MAC protocol of an existing contention access period (CAP) has a limitation of a contention length increase and a success probability decrease, and a contention-free period (CFP) is operated by reservation of an AP, and a transmission opportunity (TXOP) is allocated to particular users using a particular resource during a particular time. The CFP based on reservation in the OBSS environment attempts transmission without observing a channel condition, and thus is highly likely to collide with a reserved TXOP of another overlapping service set. Moreover, occupancy of a channel for a long time disturbs an operation of a contention period of another service set, causing an unfair resource monopoly. The TXOP operated based on reservation may include at least one of a CFP, a hybrid coordination function controlled channel access (HCCA) period, a power save multi-poll period, and a service period (SP).
Therefore, to prevent performance degradation that may occur in the OBSS environment where multiple overlapping WLAN networks coexist and to improve network efficiency, it is necessary to collect information associated with an adjacent network that may affect a network and exchange and use information between those networks. There are also needs to reserve and use a time resource or a frequency resource in which inter-network interference is minimized based on the collected information associated with the adjacent network, or to select a wireless transmission beam or sector for interference minimization or control transmission power.
Moreover, for efficient resource operation and performance improvement in the OBSS environment, there are needs for a procedure for collecting information of another service set using a station (STA) and a procedure for exchanging information between the STA and an AP as well as a method in which adjacent APs recognize each other and directly exchange information with each other.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.